1. Field
The present disclosure relates to drive shaft assemblies having end fittings, more specifically to drive shaft assemblies having welded end fittings, such as those used in ram air turbines for aerospace applications.
2. Description of Related Art
Some traditional drive shaft assemblies consist of a long tube shaft and two end fittings. The end fittings and tube shaft fit tightly together via close-tolerance interfaces. They are subsequently joined permanently together using an electron beam welding (EBW) process. It is desirable to seal the inner portion of the shaft from the atmosphere during assembly so as to prevent corrosion and pollution inside the shaft during use. The EBW process is typically performed in a vacuum chamber. Molten welds, however, have been seen to develop voids due to the surrounding vacuum causing the air trapped within the tubular shaft to escape through the EBW joint area. This weld void problem results in unsatisfactory weld quality.
However, merely evacuating the shaft before or during the weld process leads to a sealed vacuum inside the shaft after welding is complete, which can be detrimental to the performance and life span of the drive shaft assembly. Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved drive shaft assemblies and methods. The present disclosure provides a solution for this need.